Mask



FIG. 1 is a front perspective view of a mask showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 1;

FIG. 9 is an enlarged front view taken from circle 9 of FIG. 1 thereof; and,

FIG. 10 is an enlarged front view taken from circle 10 of FIG. 3.

The broken lines in the drawings depict portions of the mask that form no part of the claimed design. 

CLAIM The ornamental design for a mask, as shown and described. 